Elongated workpieces are machined by apparatus such as lathes, while being rotated about their longitudinal axis. If the workpiece deflectively revolves in this case, problems such as reduced machining accuracy and a break in the cutting tool will arise.
FIG. 11 shows a device for preventing the deflection of an elongated workpiece rotating about its longitudinal axis. This device comprises a plurality of bolts 31 screwed through a frame 30 around the elongated workpiece M, and a contact member 32 attached to the forward end of each bolt 31. The bolts are moved inwardly or outwardly of the frame 30 in accordance with the outside diameter of the workpiece M to cause the contact members 32 to support the outer periphery of the workpiece M against deflection.
With the deflection preventing device shown in FIG. 11, however, the elongated workpiece M is supported at only one point along its length, therefore greatly deflectively revolves in front and rear of the supported position as seen in FIG. 10 and can not be prevented from deflection fully effectively. When some kinds of elongated workpieces M which are different in outside diameter are to be supported by the device, the plurality of bolts 31 must be rotated individually to adjust the amount of projection of each bolt into the frame 30, hence a very cumbersome adjusting procedure.
An object of the present invention is to overcome the foregoing drawbacks of the prior art.